Polyester coated paper as a conductive sheet material

ABSTRACT

An electrically conductive sheet material prepared from paper and a particular class of polyester resins is disclosed. The use of this conductive paper as the substrate in preparing a photoconductive recording sheet material is also disclosed.

United States Patent [191 Feltzin et al.

11] 3,754,909 [451 Aug. 28, 1973 POLYESTER COATED PAPER AS A CONDUCTIVESHEET MATERIAL [75] Inventors: Joseph Feltzln; Erlch Kuehn, both ofWilmington, Del.

[73] Assignee: ICI America Inc., Wilmington, Del.

[22] Filed: Mar. 20, 1972 [21] Appl. No.: 236,192

Related U.S. Application Data [63] Continuation of Ser. No. 97,391, Dec.11, 1970,

abandoned.

[5 6] References Cited UNITED STATES PATENTS 3,248,279 4/1966 Geyer96/1.5 X

3,118,785 1/1964 Anderson et al. 117/218 X 3,703,371 ll/l972 3,703,372ll/l972 Merrill 96/L8 X 3,598,644 8/1971 Goffe et a1 117/201 FORElGNPATENTS OR APPLICATIONS 42/27193 12/1967 Japan 96/1.8

Primary Examiner Norman G. Torchin Assistant Examiner-John R. MillerAttorney-Kenneth E. Mulford et al.

[5 7 ABSTRACT An electrically conductive sheet material prepared frompaper and a particular class of polyester resins is disclosed. The useof this conductive paper as the substrate in preparing a photoconductiverecording sheet material is also disclosed.

12 Claims, No Drawings IFQLYESTER COATED PAPER AS A CONDUCTIVE SHEETMATERIAL This is a continuation, of application Ser. No. 97,391, tiledDec. 11, 1970, now abandoned.

This invention relates to an electrically conductive sheet material.More particularly this invention relates to a conductive paper preparedfrom a polyester and paper which is useful as a conductive substrate inthe preparation of photoconductive recording sheet material.

in the art of preparing photographic reproductions of originals byelectrostatic printing techniques there are two distinct methods, adirect and an indirect process. The indirect process, commonly calledxerography, employs a reuseable drum which records, by electrostaticforces, the image which is to be printed and then transfers this imageto a sheet of paper which is developed by depositing and fusing thereona xerographic ink. This results in a clear reproduction of the original.in the direct process a sheet material which has the capability ofaccepting an electrostatic image directly from the original is used andan electrostatic ink, which can be identical to a xerographic ink, isthen placed on the sheet material and the final copy prepared.

The sheet material used in the direct electrostatic printing method isusually a multi-layer material. The most common type of sheet materialuses as its base a light weight paper, such as a paper that weighs lessthan 50 pounds per ream, upon which a coating containing aphotoconductive pigment such as zinc oxide is deposited. This sheetmaterial can then receive an electrostatic image and be developed toproduce a good copy of the original. It has been found in the practiceof the direct process that paper by itself does not form a goodconductive substrate for the photoconductive layer of a photoconductiverecording material, i.e. photoconductive paper. One reason that paperdoes not form a good conductive substrate is that paper has a varyingresistivity with humidity, and this resistivity may become too great orpossibly too small to produce the proper electrical effect necessary forpreparing a good electrostatic copy. it has become prevalent in the artto impregnate paper with conductive materials, such as salts, acids,quaternary ammonium salts, and conductive polymers, which enhance theconductive property of the paper as a conductive substrate. The primarytypes of materials used in commercial photoconductive paper areconductive polymers which contain quaternary ammonium substituents. Theexact mechanism by which the conductive polymer functions is notmaterial to its effectiveness when used for photoconductive paper. Thus,although those polymers now commercially available use an ion transfertechnique due to the quaternary ammonium salt substituents, any resinwhich would enhance the electrical conductivity of paper is a candidatefor use in a conductive substrate. Not only must a resin or anothermaterial enhance the conductivity of the paper, it must also maintain arelatively constant conductivity in varying environments, especiallywith changing relative humidity. A suitable resin must also berelatively insoluble in organic solvents used in the preparation of thephotoconductive layer. These solvents are toluene and similar aromatichydrocarbon materials.

It is an object of this invention to provide a conductive paper suitablefor use in a photoconductive paper.

Hm I in this formula 2 is 0 or 1; R is a radical selected from the groupconsisting of alkylene radicals containing from I to 5 carbon atoms,oxygen, sulfur,

each E is individually either a halogen atom or a hydrogen atorn; m andn are integers frp m 0 through about 15 with the proviso that the sum ofm and n is at least 7 and usually no more than about 30; X and Y areindividually selected from the group consisting of methyl radicals andhydrogen atoms with the proviso that in any X and Y pair on adjacentcarbon atoms either X or Y is hydrogen.

In a preferred conductive polyester resin the sum of the integersrepresented by m and n in said etherified diphenol will be at most 20and at least 9.

The etherified diphenols used are prepared from a diphenol. Exemplary ofthese diphenols are 2,2-bis(4- hydroxyphenyl) propane;2,3-bis(4-hydroxyphenyl) butane; 4,4-dihydroxydiphenol;4,4'-dihydroxydiphenyl ether; bis(dichloro, difluoro-4-hydroxyphenyl)methane; 2,2-bis(2.6 dichloro-4-hydroxyphenyl) propane; bis( 2,3,5 ,6tetrafluoro-4-hydroxyphenyl) sulfoxide; 3,3-bis(2,3,5,6-tetrabromophenyl) pentane; and 4-hydroxyphenyl-Z'-chloro-4-hydroxyphenyl ketone. The diphenols areetherified for use in accordance with the present invention.Etherification may be accomplished by the addition to the diphenol ofethylene oxide, propylene oxide or a mixture of same. The ether may alsobe prepared by reacting an olefin halohydrin with a diphenol asdisclosed in U. S. Pat. No. 2,331,265. Methods of performing thereactions are well known in the art. It should be noted, however, thatwhere mixtures of alcoholic and phenolic hydroxyl groups are present,the oxide compound reacts preferentially with phenolic hydroxyl groups.Thus, when an excess of an oxide compound is reacted with a diphenol,both phenolic hydroxyls are etherified prior to any extensive etherchains being formed.

The preferred etherified diphenols within the class characterized by theabove formula are the following etherified bisphenols: polyoxypropylene2,2-bis(4- hydroxyphenyl) propane; polyoxyethylene 2,2-bis(4-hydroxyphenyl) propane; polyoxyethylene 2,2-bis(4-hydroxy-Z,6-dichloro-phenyl) propane; and polyoxypropylene 2,2-bis(4-hydroxy-2,o-dichlorophenyl) propane; wherein the number ofpolyoxyalkylene units per ylic acids are the following: phthalic acid,fumaric acid,

maieic acid, succinic acid, isophthalic acid, cyclohexane dicarboxylicacid, malonic acid, glutaric acid, and the anhydrides of these acids. Apreferred group of acids include fumaric, maleic, and their anhydrides.Mixtures of dicarboxylic acids may also be used in which case it ispreferred that at least 50 weight percent of the acids be unsaturated.

The conductive polyesters used to make the products of this inventionare prepared by the reaction of the etherified diphenol and thedicarboxylic acid, preferra bly in approximately stoichiometric amounts.The reaction may be performed in an inert atmosphere employing moderatetemperatures and substantially atmospheric pressure during an earlystage, to minimize the loss of dicarboxylic acid by volatilization. Asthe reaction proceeds the temperature may be increased and the pressurereduced. Esterification catalyst may be used although it is generallypreferred to carry out the reaction in the absence of excessive amountsof catalyst to avoid contamination of the final resinous product. It isusually desirable to include a small amount of polymerization inhibitorsuch as hydroquinone, pyrogallol, or the lilte when an usaturateddicarboxylic acid is used. The reaction temperature for preparing thefinal polyesters of this invention will usually include heating to about200C. for a portion of the reaction. The resulrant conductive polyestersusually have acid numbers less than about 30.

The conductive polyesters preferrably are applied to the paper substrateby dispersing them in a liquid vehicle. Solvents such as aromatichydrocarbons are usually suitable vehicles. Other examples are polyvinylalcohol, isopropanol, water, and ethylene glycol monoethyl etheracetate.

Preferred modifications of these conductive polyester resins, which arenot prone to becoming sticky when contacted with organic solvents, suchas toluene and styrene, which are used as carriers for thephotoconductive coatings applied to the conductive substrate, are thoseconductive polyester resins which have been modified with a modifyingagent such as either an ethylenically unsaturated monomer, apolyfunctional hydroxy compound, a polyisocyanate, a dior triamine or analkaline earth or alkali metal hydroxide. Usually from i to 50 parts byweight of said modifying agent per 100 parts of the polyester resin andmodifying agent combination are effective. Preferably 5 to 30 parts areemployed.

The ethylenically unsaturated monomers may be to modify only thoseconductive polyester resins of this invention which contain ethylenicunsaturation contributed by presence of unsaturated dicarboxylic acidresidues. in general only homopolyrnerizable ethylenically unsaturatedmonomers are used. Among the numerous ethylenically unsaturated monomerswhich may be used are styrene, vinyl toluene, chlorostyrene, divinylbenzene, diallyl phthalate, acrylonitrile, methyl methacrylate, vinylacetate, ethyl acrylate, alphamethyistyrene, vinyl pyridine, andZ-ethylhexyl acrylate.

ln preparing modifications of conductive polyester resins withethylenically unsaturated monomers a conductive polyester resin isdissolved in the ethylenically unsaturated monomer which acts as both avehicle for the conductive polyester and as a modifier. When applyingthe conductive polyester-ethylenically unsaturated monomer solution topaper to prepare a conductive substrate, accelerators, or catalysts areusually added to the solution so that the polyester may be modified bycopolymerizing with the ethylenically unsaturated monomer. Thesecatalysts include the kind frequently referred to as free radicalcatalysts, such as methyl ethyl ketone peroxide, benzoyl peroxide,tertiary butyl perbenzoate, cumene hydroperoxide, and succinic peroxide.Exemplary of accelerators are dimethyl aniline and cobalt naphthenate.

Among the polyhydroxy compounds which are contemplated as modifyingagents for the conductive polyester resins are hexamethylol melamine[commercially available as CYMEL 301], methylol urea formaldehyderesins, and methylolated phenol formaldehyde condensation products. Inall cases these modifying agents should be dispersible in any vehicleused for dissolving the conductive polyester resins. Water or toluene,benzene, and similar aromatic hydrocarbons are suitable vehicles. Thepolyhydroxy compound when dispersed along with the conductive polyesterresins within the class disclosed above is usually accompanied with anacidic catalyst to promote the cross-linking of the modifiers hydroxylgroups with residual hydroxyl and carboxyl groups of the conductivepolyester resin. These catalysts include sulfonic acid, borontrifluorideetherate, sulfuric acid, hydrochloric acid, paratoluene sulfonic acid,and similar acid catalysts.

The polyisocyanate modifications of the conductive polyester resinsdisclosed above are prepared by reacting the resins with sufficientisocyanate groups to react with residual hydroxyl groups of theconductive polyester resin. Thus to obtain complete modification withpolyisocyanate the minimum isocyanate group to residual hydroxyl groupratio is 1 but ratios as high as 3 yield acceptable modified conductivepolyester resins. Among the polyisocyanates which can be used inpreparing the modified conductive polyester resins are toluenediisocyanate, diphenyl diisocyanate, chloro-phenyl-2,4-diisocyanate,1,4-tetramethylene diisocyanate, para-phenylene-diisocyanate,3,3-dimethyl-4,4'- phenylene diisocyanate, 3 ,3 '-dimethoxy-4,4-diphenyl diisocyanate, polymethylene polyphenyl polyisocyanate (PAPI),methylene-bis(4,4'-polyphenyl polyisocyanate) (MONDUP MR), condensationproduct of a polyol and isocyanate for-example, the condensation productof 3 mols of toluene diisocyanate and 1 mol of trimethylol propane, ureacondensed isocyanates such as the one sold under the tradename DESMODURN and having the formula and other polymethylene polyphenyl isocyanatescontaining an averate of from 2 through about 3.3 isocyanate groups permolecule. These isocyanates can be used to cross-link the unsaturated orthe saturated conductive polyester resins. Preferably saidpo1yisocyanates contain an average of more than 2.5 isocyanate groupsper molecule. The crosslinking may be aided by the addition of standardcatalysts used in promoting urethane reactions. Exemplary of thesecatalysts are dibutyl tin dilaurate, trimethyl amine, N-methylpiperazine and N-methyl morpholine. The isocyanate and polyester areusually applied to the paper from an aromatic organic solvent such asbenzene or toluene. However, where a catalyst is used the catalyst isusually added just prior to application to minimize crosslinking beforeapplication of the coating.

The diand triamine and alkaline earth or alkali metal hydroxidemodifications of the conductive polyester resins of this invention areprepared by mixing a conductive polyester resin with an amine orhydroxide at about room temperature and mixing for to 30 minutes. Theconductive polyesters are usually liquid, but the conductivepolyester-amine or inorganic salt mixture usually takes on a gel likeconsistency. The products are water soluble and relatively insoluble inaromatic hydrocarbons, and thus they may be applied from water solution.The amines are generally saturated acyclic, alicyclic, or aromatic.Exemplary of amines contemplated are triethylene diamine,cyclohexyldiamine, piperidine, hexamethylene triamine, tetraethylenetriamine, and benzoguanamine. Exemplary of the hydroxides are calcium,barium, lithium, sodium, and potassium hydroxide.

In order for those skilled in the art to better understand the conceptsof and the practice of this invention the following non-limitingexamples for the preparation of the conductive polyester resinsdisclosed above are given:

EXAMPLE 1 5,940 grams of polyoxypropylene(16)-2,2-bis (4- hydroxyphenyl)propane; 575 grams of fumaric acid; and 2 grams of hydroquinone areadded to a fournecked, four-liter reaction vessel. This reaction mixtureis purged with nitrogen and heated to 210C. The water of esterificationis removed through a condenser as it is formed. The acid value of thereaction mixture is determined by the taking of hourly samples. When theacid value falls below 25, the reaction is stopped by removing themixture from the heat source and pouring the reaction mixture into anopen pan. The resulting polyester resin is a viscous liquid.

EXAMPLE 2 3,460 grams of polyoxyethylene( 12)-2,2-bis(4- hydroxy-phenyl)propane; 540 grams of fumaric acid; and 2.0 grams of hydroquinone areplaced in a 4- necked, 4-liter reaction vessel. The reaction mixture isheated with stirring to a temperature of 210C. 1- 5, and the reactionvessel is purged with nitrogen during the heat up period. Maintainingthe 210C. and the inert nitrogen atmosphere, hourly samples of thereaction mixture are taken and when the acid value of the polyesterreaches less than 25, the reaction mixture is removed from the heat andpoured into an open pan for cooling. During the course of the reactionthe water of esterification is continually removed. The resultant cooledresin is a viscous liquid polyester with an acid value of 19.2.

EXAMPLE 3 According to the procedure of Example 1, 1,436 grams ofpolyoxypropylene(9)-2,2-bis(4- hydroxyphenyl) propane, 232 grams offumaric acid, and 1.1 gram of hydroquinone are added to a 4-necked4-liter reaction vessel. The reaction mixture is heated to 205C. andsamples taken every hour and the acid value determined. When the acidvalue is determined to be less than about 20 the reaction vessel isremoved from the heat source and the resin poured into an open pan forcooling. The resulting resin is a viscous liquid polyester.

EXAMPLE 4 3,782 grams of polyoxypropylene(16)-2,2-bis(2,6-difluoro-4-hydroxyphenyl) propane and 434 grams of phthalic anhydrideare added to a 4-liter, 4-necked reaction vessel and reacted accordingto the procedure of Example 2, at 205C. Hourly samples are removed fromthe reaction mixture and when the acid value is less than about 30 theresin is removed from the heat source and cooled in an open pan. Theresulting polyester resin is a viscous liquid.

EXAMPLE 5 According to the procedure of Example 1, 1,952 grams ofpolyoxyethylene(20)-4,4'-diphenyl ketone, 396 grams of glutaric acid,and 1.1 grams of hydroquinone are added to a 4-necked, 4-liter reactionvessel. The reaction is maintained at 200C. and hourly samples taken andthe acid value of these samples determined. When the acid value is lessthan 20, the reaction mixture is removed from the heat source and cooledin an open pan. The resultant resin is a viscous liquid polyester resin.

EXAMPLE 6 According to the procedure of Example 1, 583 grams ofpolyoxyethylene(9)-2,2-bis(4-hydroxyphenyl) propane, 540 grams offumaric acid and 2 grams of hydroquinone are reacted at 210C. When theacid value of the reaction mixture reaches less than about 25 thereaction is stopped. The product is a viscous liquid resin with an acidvalue of 15.1.

The conductive sheet material of this invention may be prepared bycoating a paper, suitably a bond paper, similar to that described in U.S. Pat. No. 3,501,295, Column 5, line 5 3 through Column 6, line 43,with, for example, from 0.5 to 5.0 pounds of said conductive polyesterresins per ream of paper; in which case the conductive polyester resinportion of the conductive substrate will be from about 1 to about 15percent of the base paper. Papers used for preparing photoconductivepaper include, for example glassine paper and paper sold by Riegel PaperCompany under the Trade No. EC-38-XA and No. EC-35-XE.

In general the conductive substrate of this invention is prepared bycoating a sheet of paper with a conductive polyester composition, whichmay include a modifier, in a vehicle. The conductive polyester resinconcentration will normally be from about 1 through 95 weight percent ofsaid coating composition. The coating compositions applied by anystandard paper coating method such as roller coating, size press, etc.depending upon the base paper stock used. The vehicle may be, forexample, water or an organic aromatic compound such as benzene, toluene,or ethyl benzene. After application the coated paper is dried drivingoff the vehicle.

To increase the flim forming tendencies of the conductive polyester andto allow easier manipulation of the viscosity of the polymer solutionfilm-extending materials are preferably incorporated in the solution.These materials may be added in a weight ratio of from 3 to 0.5 parts offilm extender per part of conductive polyester resin. The viscosity ofthe final formulation; that is, the polymer, the film extender, and thesolvent, is adjusted so that the total viscosity is below 20,000centipoises. When a film extender is used it is sometimes desireable toemploy an emulsifier to aid in dispersing the film extender in thevehicle. Exemplary of the emulsifiers are polyoxyethylene hexitol fattyacid esters, and polyoxyethylene hexitan fatty acid esters. Exemplary offilm extenders are pigments, starches and rubber-like polymers; specificexamples are TiO kaolin clay, butadiene-styrene copolymers, and lowmolecular weight polyethylene or polypropylene.

A laboratory method of coating paper employs wire wound rods. Aconductive polyester resin solution is poured onto the paper to becoated in one comer or at one edge of the paper. A wire wound rod isthen passed across the paper starting at the solution containing edge.The thickness of the coating depends upon the wire thickness of the wirewound rod. The coated paper is then dried at between 50 and 120C. toremove all residual solvent. The resulting dry paper is relativelyimpenneable to organic solvents used for depositing the photoconductivezinc oxide compositions of the final photoconductive paper.

Conductive substrates of this invention are prepared by using the abovewire wound rod technique of spreading the resin on paper. The conductiveresin may be applied as a conductive coating composition in a liquidvehicle as a solution or dispersion. The resins are dispersed ordissolved in the liquid vehicle by blending, mixing, stirring, or byother mechanical methods. Where a modifying agent, a catalyst, a filmextender, or other additional ingredients which will make up part of thefinal coating are to be applied they are dissolved or dispersed with theconductive resin in the liquid vehicle. The conductive coatingcompositions Examples 7-20, which are tabulated Table I, are prepared bymixing all the ingredients into a vehicle, which is listed as thesolvent in Table I.

Table I lists various conductive coating compositions which are appliedto either aluminum foil or paper. Examples 7 to which use aluminum foilare not representative of the conductive substrates of this inventionbut are used to illustrate the good conductive properties of thecoatings used in accordance with this invention. Thus when a conductivecoating is applied on a conductive substrate, such as aluminum foil asin Examples 7 to 15, the conductive properties of the coating can bedetermined independently of the substrate by subjecting the coatedaluminum foil to a voltage discharge of, for example, 9000 volts forabout 5 seconds in a corona dishcarge unit capable of maintaining an8500 to 9500 volt field. It will be found that no charge is accepted bythe coated foil of Example 7-15. This result indicates that the resincoating is indeed very conductive.

Examples 16-20 in Table I illustrate conductive substrates of particularconductive coating compositions on paper. These conductive substratesare prepared in accordance with the aforementioned coating procedure,and are electrically conductive sheet materials of this invention. Whenthese conductive substrates are subjected to a corona discharge, inaccordance with the procedure discussed above for coated aluminum foil,the charge acceptance is also zero.

The preferred system of drying the coating after coating the paper toresult in the final conductive substrate varies depending upon theconductive polyester resin composition. These procedures are shown as(A) through (D) in Table I and correspond to the following procedures:

Procedure A. A conductive polyester resin is dissolved in a solvent andcoated on paper or aluminum foil using a wire wound rod supplied by R.D. Specialities of Webster, NY. The paper is then dried at C. to C. for2 to 20 minutes resulting in a dry, flexible conductive paper orsubstrate.

Procedure B. A conductive polyester resin containing ethylenicunsaturation within the class of conductive polyester resins disclosedabove is dissolved in ethylenically unsaturated monomer along with afree radical catalyst and the resulting solution is coated as inProcedure A on aluminum foil or paper sheets and cured at 100C. for 20minutes.

Procedure C. A conductive polyester resin within the class of conductivepolyester resins disclosed above is dispersed in water with an acidcatalyst and polyhydroxy compound within the class disclosed above. Thisdispersion is coated as in Procedure A on aluminum foil or paper andcured for 30 minutes at 100 C.

Procedure D. A conductive polyester resin within the class disclosedabove is mixed with a polyisocyanate in an aromatic hydrocarbon. Thismixture is coated as in Procedure A on aluminum foil or paper and curedat room temperature for an hour.

In Table I the catalyst is listed as W, X, Y, or Z. W is a mixture of 1part benzoyl peroxide and 0.4 parts of dimethyl aniline by weight, X isparatoluene sulfoncic acid, Y is triethylene diamine and Z is dibutyltin dilaurate. The following additional abbreviations are used in TableI: TDI toluene diisocyanate; HMM Hexamethylolmelamine; EG MBA-Ethyleneglycol monoethyl ether acetate; PTDI condensation product of 3 mols oftoluenediisocyanate and 1 mol of trimethylol propane; and EC-3S-XE Abond paper produced by the Reigel Paper Company. All quantities in Tablel are parts by weight.

TABLE I.-G onnuc'rive SUBSTRATE Conductive coating compositions Dry-Lbs. Conductive ing coutpolyester I Film Cataproing/ of Parts ModifierParts Solvent Parts extender Parts lyst Parts Substrate cedurv roamExample:

7 Example 1.. 50 Alfugpiimm A 4 O1 1.4 .....do B 5 1.4 .....do.. B 5

..(10 2 ...do. C 5

11 ..do 3 do..... C 3

12 ..do...... 0.3 .....do D 2 13.. ...(lo 0.3 .....do l) 4 14.. ..(lo0.3 .....do 3 15. luxamplvh EC35XE. A 4 16.. lCxamp|o2.. 70 EC-35XE A 417 Exmnnlol EC-35XE.. A 4

2.) 1x ..do lsopropauol. X :3 l I(J--Xl 4 Po yvluyl 8 alcohol.

lsopropanol. 20 Kaolin 70 EC-35-XE A 4 10 1 ..do 20.2 Water 312 Clay.

Kaolin 70 play. T102 5 20 ..do 39 Triethyleneamine.. 1 Water 300Dogg'fiLatex 70 EC-35-XE .A 4

1 Conductive coating contains 0.5 part of polyoxycthylene (20) sorbitanmonooleatc as an emulsifier.

A number of resins are available which may be used as binder resins inthe photoconductive composition which comprises the top layer of aphotoconductive paper. Among these binder resins are silicone resins,cellulose esters (such as cellulose acetate, cellulose acetate butyrate,and cellulose nitrate), cellulose ethers (such as ethyl cellulose andmethyl cellulose), polyvinyl acetate, polystyrene, acrylics, andpolyesters.

The photoconductive composition may in general be comprised of fromabout 15 parts to 2.5 parts of a photoconductive pigment per part byweight of binder resin. In preferred photoconductive compositions theratio of photoconductive pigment to binder resin is from 9 to 5.

Polyester resins, which may be advantageously used as binder resins in aphotoconductive composition, are those electrically insulating polyesterresins prepared from a dicarboxylic acid and a polyol composition whichcomprises a short chain etherified dephenol, or a mixture of a dihydroxyalkane and a short chain etherified diphenol.

'A 50% water solution of a lmladienc-styrenc copolymor of Dow ChemicalCo.

tion may be represented by the following formula:

selected from the group consisting of alkylene radicals of l to 5 carbonatoms, oxygen, sulfur,

A is individually selected from a halogen atom or hydrogen atom, theletters m and n are integers from 0 through 6 with the proviso that thesum of m and n is at least about 2 and less than 7; X and Y are radicalswhich are individually selected from the following group: alkyl radicalsof l to 3 carbon atoms, a phenyl radical, or a hydrogen atom; providedthat in any and Y pair an adjacent carbon atom either X or Y is ahydrogen atom.

A preferred group of short chain etherified diphenols within the aboveformula include those where A is a chlorine atom or a hydrogen atomand/or R is an alkylene radical containing 1 to 3 carbon atoms and X'andY are either hydrogen or a methyl radical. In this preferred group theaverage sum of n and m is at most about 3.

Examples of short chain etherified diphenols within the above formulainclude the following:

polyoxyethylene-( 3 )-2,2-bis( 4-hydroxyphenyl) propane;

polyoxystyrene( 6 )-bis( 2 ,6-dibromo-4- hydroxyphenyl) methane;

polyoxybutylene(2.5 )-bis(4-hydroxyphenyl) ketone;

poloxyethylene(3 )-bis( 4-hydroxphenyl) ether;

polyoxystyrene(2.8)-bis(2,6-dibromo-4- hydroxyphenyl) thioether;

polyoxypropylene( 3 )bis(4-hydroxyphenyl) sulfone;

polyoxystyrene( 2 )-bis( 2,6-dichloro-4- hydroxyphenyl) ethane;

polyoxyethylene( 3 )-bis( 4-hydroxyphenyl) thioether;

polyoxypropylene(4)-4,4l'-bisphenol; polyoxyethylene( 65 )-bis( 2,3,6-fluorodichloro-4- hydroxyphenyl) ether; polyoxyethylene(3.5)-4,4-bis(4-hydroxyphenyl) pentane; polyoxystyrene(4)-2-fluoro-4-hydroxy-phenyl 4-hydroxypheny1 sulfoxide; andpolyoxybutylene(2)-3,2-bis(2,3,6- tribromo-4-hydroxyphenyl) butane.

A preferred class of polyester resins within the above class are thosecontaining 2,2-bis(4-hydroxyphenyl) propane or the corresponding2,6,2',6'-tetrachloro, tetrabromo, or tetrafluoro bisphenol alkoxylatedwith from two to four mols of propylene or ethylene oxide per mol ofbisphenol.

The dihydroxy alkanes which can be present at a level up to 60% byweight of the polyol composition used in preparing the non-conductivepolyester resins of the photoconductive composition used to prepareelectrofax paper in accordance with this invention are dihydroxy alkanescontaining from 2 to 8 carbon atoms. A preferred group of dihydroxyalkanes include propylene glycol, ethylene gylcol, and neopentyl glycol.Examples of other dihydroxy alkanes which can be used include 1,3-dihydroxybutane, 1,4- dihydroxypentane, 1 ,Z-dihydroxyhexane, 2,3-dihydroxybutane, and 1,2-dihydroxyoctane.

In addition to said dihydroxy alkanes or in lieu of same up to about 3weight percent of said polyol composition can be comprised of apolyhydroxy alkane containing 3 to 6 carbon atoms and 3 to 6 hydroxylgroups or etherified derivatives of said polyhydroxy alkanes wherein theetherifying compounds are preferably ethylene or propylene oxide andthere is up to 10 mols of oxide per hydroxyl group of said polyhydroxyalkane and preferably at least 1 mol of oxide per hydroxy group.Exemplary of these polyhydroxy alkanes and the etherified polyhydroxyalkanes are sorbitol; erythritol, xylitol; pentaerythritol;1,2,3-butane-tn'ol; l,2,5,6-hexanetetrol; polyoxyethylene(3) glycerol;polyoxypropylene(25) sorbitol; polyoxyethylene(6) 1,2,4,-butane-trioland polyoxypropylene(50) manni-- tol.

In general the dicarboxylic acid used in preparing the non-conductivepolyester resin may be saturated or unsaturated and may containsubstituents such as halogen. Among these dicarboxylic acids are thefollowing; phthalic acid, furmaric acid, maleic acid, isophthalic acid,malonic acid, glutaric acid, adipic acid, and the anhydrides of theseacids. A preferred group of acids and anhydrides include fumaric,maleic, and succinic acids.

The electrically insulating polyester resins are usually prepared by thereaction of a dicarboxylic acid with a polyol composition selected fromthose disclosed above. The reaction may be performed in an inertatmosphere employing moderate temperatures and substantially atmosphericpressures during the early stage, thus minimizing the loss ofdicarboxylic acid by volatilization. As the reaction proceeds thetemperature may be increased and the pressure reduced. Esterificationcatalyst may be used although it is generally preferred to carry out thereaction in the absence of excessive amounts of catalyst to avoidcontamination of the final resinous product. When an unsaturateddicarboxylic acid is used it is usually desirable to include a smallamount of polymerization inhibitor such as hydroquinone, or pyrogallol.The reaction temperature required for preparing the final polyesterswill usually include heating to about 200C. for a portion of thereaction. The resultant polyesters have low acid numbers; that is acidnumbers less than about 30. Usually the ratio of carboxyl groups andhydroxyl groups in the reaction mixture used for preparing the polyesterresins of this invention is about 1. However, ratios as low as about 0.8and as high as about 1.2 can readily be used.

In order for those skilled in the art to better understand thepreparation of these insulating polyester resins the following examplesare given.

EXAMPLE 21 1,865 grams of polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl) propane and 2.9 grams of polyoxypropylene(6)sorbitol arecharged to a 3 liter, 4 necked, round-bottom reaction flask which isfitted with a thermometer, a stainlesssteel stirrer, a gas inlet tube,and a downward condenser. The flask is supported in a GLAS-COL electricheating mantle. Through the gas inlet tube nitrogen gas is allowed toflow sparging the polyol blend and resulting in an inert atmospherein-the reaction vessel. The agitator and heating mantel are thenactivated and the polyol composition is heated to 50C. at which time 628grams of fumaric acid and 1.25 grams of hydroquinone are addedto thereaction vessel. The nitrogen gas flow was then regulated at a settingof 2.5 on a SHO-RATE meter of the Brooks Rotometer Company. The reactionmass is heated to a temperature of 210C. over a period of 5 hours. Waterof the esterifieation reaction is removed as it is formed and the massis maintained at 210C. for an additional 6 A hours. The course of thereaction is followed by acid value determinations at hourly intervals.At the end of the reaction, when an acid value of about 20 is achieved,the resin is cooled to room temperature. The resin has an acid value of18.6, a ball and ring softening point of 104C., a tack point of C., anda liquid point of C. The ratio of hydroxyl groups and carboxyl groups inthe preparation of this resin is 1 to 1.

EXAMPLE 22 In accordance with the procedure of Example 1, 985 grams ofpolyoxyethylene( 3) bis( 4-hydroxyphenyl) ketone and 44.3 grams ofpolyoxyethylene(30) pentaerythritol are placed in a 3 liter,round-bottom flask. This mixture is heated and when the reactiontemperature reaches 50C. 348 grams of succinic acid are added. Thereaction mixture is then heated to a temperature of 215C. and the waterof reaction is continually removed. The course of the reaction isfollowed by taking hourly samples in determining the acid value. Afteran acid value of 30 is reached the heat is removed and the reactionmixture is slowly cooled to room temperature. The resulting polyester ishard, tough and solid.

EXAMPLE 23 According to the procedure of Example 1, 2190 grams ofpolyoxyethylene(2.5)-2,2-bis(4-hydroxy2,6- chlorophenyl) propane and 21grams of polyoxyethylene(12) xylitol are placed in a 4 liter flask. Thismixture is heated and when a temperature of 50C. is obtained, 465 gramsof maleic acid is added. The heating is continued until a temperature of210C. is achieved at which point the temperature is maintained at 210C.The water of esterification is removed as it is formed through acondenser. The acid value of the reaction mixture is tested at hourlyintervals and when the acid number is less than 30, the reaction mixtureis cooled to room temperature. The resultant polyester is a tough solidresin.

EXAMPLE 24 pigment in a mechanical mixing device such as a rubber mill,ball mill or knife mill in the presence or absence of a solvent for thebinder resin. Any other additives such as a sensitizer is addedsimultaneously.

The photoconductive compositions may then be coated on conductive sheetmaterial of this invention by standard paper coating techniques such asroller coating, size press, air knife or trailing blade coating. In thelaboratory the aforementioned wire wound rod technique is desirablyused.

Examples 25 to 36 tabulated in Table 11 illustrate photoconductive paperof the invention. The photoconductive composition listed in Table 11 areprepared by dissolving the electrically insulating polyester in onethird of the solvent, i.e. toluene, and mixing the so formed solutionwith a slurry of the photoconductive pigment in the remaining two thirdsof the solvent. This mixture is then charged to an 8580 Eberbachstainless steel container fitted for a WARlNG Blendor and ground to afiness of 5 to 6.5 of the N. S. Hegman scale. The parts listed in Table11 are parts by weight.

The products of Examples 25-36 are exceptionally good photoconductivepapers for the direct electrostatic process. When prints were preparedfrom the photoconductive paper illustrated in Table II, excellentclarity and black and white contrast are observed. This photoconductivepaper can be used in any electrostatic direct process machine whether itis a dry or a wet developing machine.

TABLE II.-ELECTROFAX PHOTOCONDUCTIVE PAPER Photoconductive compositionPhotoconductive Resin Solvent pigment sensitizer Pounds} Conductive TypeParts Type Parts Type Parts 'Iypn Parts ream paper of Exumplc:

25. Example 21. 16. 75 Toluene. 100 Z110 133. 3 A .00133 14 Example 15.26... rlo.. 1G. 75 .,.1lo 100 Z110 133.3 A .00133 14 Example 16. 27-.16.75 lo 100 ZnO 133.3 A .00133 14 Example 17. 23 10. 75 .dn.... 100 ZnU133.3 A .00133 H Examplev 18. 29.. 16. 75 ...(lo. 100 Z110 133.3 A.00133 14 Example 10. 30.. 16. 75 l0. 100 Z110 133.3 A 00133 1 1 Example.20. 31. 20. ...(l0. 120 Z110 166 ll 0. 0015 12 Example 15. 32. 20. 50(10.. 120 Z110 166 ll 0. 00.2 20 Example 18. 33. 20.50 do. 120 Z110 1661!- 0.001 21 Example 16. 34 De Soto E041.-. 14.00 .do- 80 ZnO 106.6 A 0.00106 15 Example 15.

35 Arotap 3201..- 14.00 d0.. 80 ZnO 106.6 A 0.00106 15 Do.

36 Gelva 269 13.00 ...do 80 ZnO 106.6 A 0.00106 15 Do.

acid value is determined. When the acid value is less than 25 but morethan 15, teh reaction mixture is removed from the heat source andallowed to cool to room temperature on a tray cooler. The final acidvalue for this resin in 16.4 and the resin exhibits a ball and ringsoftening point of 103C.

In preparing the photoconductive composition used in coating theconductive substrate of this invention it is frequently desireable toinclude sensitizers such as bromophenol blue, dibromofluorescein,acrydin yellow, rose bengal, disodium fluorescein, alizarin cyaninegreen GWA, and other sensitizers as illustrated in U. S. Pat. No.3,245,735 at line 54, column 15. The sensitizer concentration will varyfrom about 0.01 to about 5.0 weight percent based upon thephotoconductive material, with a preferred concentration of 0.01 to 0.1.

The photoconductive compositions may be prepared by mixing the binderresin and the photoconductive The zinc oxide listed in Table 11 isphotoconductive quality and sold under the trademark of PHOTOX zincoxide. The sensitizer listed as part of the photoconductive compositionin Table 11 is a mixture of bromophenol blue, disodium fluorescein,alizarin cyanine green GWA, and auramin 0 in a 1/l.4/l/0.1 weight ratiorespectively and labeled sensitizer A or a 10 to 1 blend of rose bengaland bromophenol blue labeled sensitizer B. Three commercial resins arelisted in Table II; namely, DE SOTO E041, a styrene-acrylic copolymer ofDE SOTO Chemical Co.; AROTAP 3201, an alkyd resin produced by AshlandOil Co.; and GELVA 269, a vinyl polymer of the Monsanto Chemical Co.

Having thus described the invention the following is claimed:

1. An electrically conductive sheet material which comprises papercoated with a conductive polyester resin of a dicarboxylic acid and anetherified diphenol wherein z is or 1; R is a radical selected from thegroup consisting of alkylene radicals containing from 1 to carbon atoms,oxygen, sulfur,

each E is individually selected from a halogen atom or a hydrogen atom;m and n are integers from 0 through about with the proviso that the sumof m and n is at least 7.0 through about 30; and X and Y areindividually selected from the group consisting of a methyl radical anda hydrogen atom with the proviso that in any X and Y pair on adjacentcarbon atoms either X or Y is hydrogen.

2. An electrically conductive sheet material according to claim 1wherein said dicarboxylic acid is selected from unsaturated dicarboxylicacids and mixtures of unsaturated dicarboxylic acids containing at leastabout 50% unsaturated dicarboxylic acid and wherein in said etherifieddiphenol the sum of m and n is at most and at least 9.

3. An electrically conductive sheet material according to claim 1wherein the said etherified diphenol is selected from the groupconsisting of polyoxypropylene 2,2-bis(4-hydroxyphenyl) propane;polyoxyethylene 2,2-bis(4-hydroxyphenyl propane; polyoxyethylene 2,-2-bis(4-hydroxy-2,6-dichloro-phenyl) propane; and polyoxypropylene2,2-bis(4-hydroxy-2,6- dichlorophenyl) propane; and wherein the numberof polyoxypropylene or polyoxyethylene units per mol of etherifieddiphenol is from 9 to 20.

4. An electrically conductive sheet material according to claim 1wherein said conductive polyester resin has been modified with amodifying agent selected from the group consisting of an ethylenicallyunsaturated monomer, a polyfunctional hydroxy compound dispersible inaromatic hydrocarbons, a polyisocyanate, a dior triamine, and analkaline earth or alkali metal hydroxide and wherein from 1 to 50 partsof modifying agent are present per 100 parts of the combination ofpolyester resin and modifying agent.

5. An electrically conductive sheet material according to claim 4wherein said ethylenically unsaturated monomer is homopolymerizable,said polyisocyanate contains an average of more than 2.5 isocyanategroups per molecule, and said diand triamines are either saturatedacyclic, alicyclic, or aromatic compounds.

6. An electrically conductive sheet material according to claim 1wherein a film extending material is in admixture with said conductivepolyester resin in a weight ratio of from 3 to 0.5 parts of filmextender to polyester resin.

7. A photoconductive paper composition which comrial to said binderresin is from l5 to 2.5.

8. A photoconductive paper composition which comprises an electricallyconductive sheet material of claim 4 and a photoconductive compositioncoated thereon which comprises a photoconductive pigment and a binderresin wherein the weight ratio of said photoconductive material to saidbinder resin is from 15 to 2.5.

9. A photoconductive paper composition which comprises an electricallyconductive sheet material of claim 1 coated with a photoconductivecomposition comprising a photoconductive pigment and a binder resinwherein said binder resin is an electrically nonconductive polyesterresin of a dicarboxylic acid and a polyol composition which contains ashort chain etherified diphenol which may be represented by the formula:

wherein 2 an integer of 0 or 1; R is a radical selected from the groupconsisting of alkylene radicals of l to 5 carbon atoms, oxygen, sulfur,

A is individually selected from a halogen atom or a hydrogen atom; theletters m and n are integers from 0 through 6 with the proviso that thesum of m and n is at least 2 and less than 7; and X and Y are radicalswhich are individually selected from the group consisting of alkylradicals containing 1 to 3 carbon atoms, a phenyl radical, and ahydrogen atom, with the proviso that in any X and Y pair on adjacentcarbon atoms either X or Y is a hydrogen atom.

10. A photoconductive paper composition comprises the electricallyconductive sheet material of claim 4 coated with a photoconductivecomposition consisting of a photoconductive pigment and binder resinwherein said binder resin is an electrically nonconductive polyesterresin of a dicarboxylic acid and a polyol composition which contains ashort chain etherified diphenol which may be represented by the formula:

which wherein 1 represents an integer of or 1; R is a radical selectedfrom the group consisting of alkylene radicals of l to 5 carbon atoms,oxygen, sulfur 1 1:0, s=o and o=s=0;

A is individually selected from a halogen atom or a hydrogen atom; theletters m and n are integers from 0 through 6 with the proviso that thesum of m and n is at least 2 and less than 7; and X and Y are radicalswhich are individually selected from the group consisting of alkylradicals containing 1 to 3 carbon atoms, a phenyl radical, or a hydrogenatom, with the proviso that in any X and Y pair on adjacent carbon atomseither X or Y is a hydrogen atom.

11. A photoconductive paper composition according to claim 9 whereinsaid polyol composition includes up to 60 weight percent of a dihydroxyalkane containing from 2 to 8 carbon atoms.

12. A photoconductive paper composition according to claim 9 whereinsaid polyol composition contains up to about 3 weight percent of apolyhydroxy alkane containing from 3 to 6 carbon atoms and from 3 to 6groups or an ethylene or propylene oxide derivative of said polyhydroxyalkane, said derivative containing up to 10 mols of oxide per hydroxylgroup of said polyhydroxy alkane.

mg?" I UNITED stuns PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,754,909 notod August 28, l 973 ma Joseph Feltzin and Erich Kuehn 7 Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

"I Column 4, line 62, (MONDUP MR) should read (MONDUR HR) Column 5, line8, "averate" should read average Column 7, line: 15, "flim" should readfilm Column 8, line 32, "Speciali" should read Special Column 8, line47, after the word "water" and before the word "with" insert the wordalong Column 8, line" 60, "sulfoncic" should read sulfonic Column 9,line 55, after the word "to" and before the word "2.5" insert the wordabout Column 9,. line 65, "dephenol," should read diphenol, Column 11,line 59, "furmaric" should read fumaric Column 11, line 59, after thewords "maleic acid," and before f the word "isophthalic" insert thewords sucoinic acid,

Column 13, line 52, "teh" should read the Q Column 16, Claim 9, line 34,after the word "2 and before the word "an" insert the word representsColumn 16, Claim 10, line 53, after the word "and" and before the word"binder" insert the word a Column 18, Claim 12, line 9, at the end ofthe line and after the words and from 3 to 6" insert the word hydroxyl LSigned and sealed this 9th day of July 1974 (SEAL) Attest: EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents

2. An electrically conductive sheet material according to claim 1wherein said dicarboxylic acid is selected from unsaturated dicarboxylicacids and mixtures of unsaturated dicarboxylic acids containing at leastabout 50% unsaturated dicarboxylic acid and wherein in said etherifieddiphenol the sum of m and n is at most 20 and at least
 9. 3. Anelectrically conductive sheet material according to claim 1 wherein thesaid etherified diphenol is selected from the group consisting ofpolyoxypropylene 2,2-bis(4-hydroxyphenyl) propane; polyoxyethylene2,2-bis(4-hydroxyphenyl propane; polyoxyethylene2,2-bis(4-hydroxy-2,6-dichloro-phenyl) propane; and polyoxypropylene2,2-bis(4-hydroxy-2,6-dichlorophenyl) propane; and wherein the number ofpolyoxypropylene or polyoxyethylene units per mol of etherified diphenolis from 9 to
 20. 4. An electrically conductive sheet material accordingto claim 1 wherein said conductive polyester resin has been modifiedwith a modifying agent selected from the group consisting of anethylenically unsaturated monomer, a polyfunctional hydroxy compounddispersible in aromatic hydrocarbons, a polyisocyanate, a di- ortriamine, and an alkaline earth or alkali metal hydroxide and whereinfrom 1 to 50 parts of modifying agent are present per 100 parts of thecombination of polyester resin and modifying agent.
 5. An electricallyconductive sheet material according to claim 4 wherein saidethylenically unsaturated monomer is homopolymerizable, saidpolyisocyanate contains an average of more than 2.5 isocyanate groupsper molecule, and said di- and triamines are either saturated acyclic,alicyclic, or aromatic compounds.
 6. An electrically conductive sheetmaterial according to claim 1 wherein a film extending material is inadmixture with said conductive polyester resin in a weight ratio of from3 to 0.5 parts of film extender to polyester resin.
 7. A photoconductivepaper composition which comprises an electrically conductive sheetmaterial of claim 1 coated with a photoconductive composition containinga photoconductive pigment and a binder resin wherein the weight ratio ofsaid photoconductive material to said binder resin is from 15 to 2.5. 8.A photoconductive paper composition which comprises an electricallyconductive sheet material of claim 4 and a photoconductive compositioncoated thereon which comprises a photoconductive pigment and a binderresin wherein the weight ratio of said photoconductive material to saidbinder resin is from 15 to 2.5.
 9. A photoconductive paper compositionwhich comprises an electrically conductive sheet material of claim 1coated with a photoconductive composition comprising a photoconductivepigment and a binder resin wherein said binder resin is an electricallynon-conductive polyester resin of a dicarboxylic acid and a polyolcomposition which contains a short chain etherified diphenol which maybe represented by the formula:
 10. A photoconductive paper compositionwhich comprises the electrically conductive sheet material of claim 4coated with a photoconductive composition consisting of aphotoconductive pigment and binder resin wherein said binder resin is anelectrically non-conductive polyester resin of a dicarboxylic acid and apolyol composition which contains a short chain etherified diphenolwhich may be represented by the formula:
 11. A photoconductive papercomposition according to claim 9 wherein said polyol compositionincludes up to 60 weight percent of a dihydroxy alkAne containing from 2to 8 carbon atoms.
 12. A photoconductive paper composition according toclaim 9 wherein said polyol composition contains up to about 3 weightpercent of a polyhydroxy alkane containing from 3 to 6 carbon atoms andfrom 3 to 6 groups or an ethylene or propylene oxide derivative of saidpolyhydroxy alkane, said derivative containing up to 10 mols of oxideper hydroxyl group of said polyhydroxy alkane.